George Patterson ) wrote:
: Doug wrote:
:
: Expensive? Yes, but a permanent solution.
:
: Not at all. When New Orleans was settled, it was above sea level. The
: ground has subsided and is continuing to do so.
:

The Mississippi has contributed to the problem by building its own
bed too high...

http://www.uh.edu/engines/epi1135.htm
No. 1135: Ol' Man River


"...But here the Mississippi has built its own bed too high, and is
ready to leave it. That threat has been mounting steadily. By
WW-II, a third of the Mississippi was overflowing into the Old
River and from there to the Atchafalaya River. The Atchafalaya
meanders down through the Cajun parishes of south central
Louisiana. It was about to become the outlet of the Mississippi.
The Corps of Engineers responded by building dams and locks.

The Mississippi has been jumping about like that for thousands of
years. Most of Louisiana is made of sand and silt dumped by the
River. The Mississippi was shifting its bed during the Trojan Wars.
It was shifting again while the Romans built their aqueducts. The
Battle of Hastings occurred during its last major move.

Today, a striking feature of the Louisiana map is a long arm of
land reaching from New Orleans to the southeast, far into the Gulf
-- the lengthening bed of the Mississippi. That arm of silt was a
mere stump in my 1898 Britannica.

[snip]

We've contained the Mississippi's attempt to move for a while. But
move it will -- sooner or later. One big flood and it will break
through those fragile barricades to reach the low ground it hungers
for. When that happens, two hundred miles of fresh-water ports will
be left dry, unless we cut a salt-water trench across Louisiana.

Many observers look on attempts to hold the Mississippi as pure
hubris. One says, The three most arrogant human projects imaginable
are, in descending order, to steal the sun, to make the rivers run
backward, and to contain the Mississippi.

The longer we hold this tiger by the tail, the more committed we
are to a task that's more difficult every year. The Mississippi
warns us, yet again, that nature's intent is inexorable. Nature
will yield to our will -- but only so far, and only for a while..."


--Jerry Leslie
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